Lovely précis of the history of the English language, mav. Redclaw's question, however, was about an exclusive vs. inclusive we. The original mention of singular vs. plural you was merely for reference.

There was, in OE, a distinction made between dual and plural 1st person pronouns, wit and we respectively, in the nominative case. As far as I know there was no distinction in either of those between including and excluding the hearer.